Claim: The Phrase “Vaccines Do Not Cause Autism” is Not Supported By Science

Verdict: False and misleading

“The phrase ‘Vaccines do not cause autism’ is not supported by science.”

RFK, Jr.  

The CDC quietly updated its page on the link between vaccines and autism this week. Of note, it argues – like RFK, Jr. did in the quote above – that it is not an evidence-based claim to say “vaccines do not cause autism.”

But, is it?

There is No Evidence That Vaccines Cause Autism

Studies consistently show that specific vaccine-related concerns about autism – the Measles-Mumps-Rubella vaccine (MMR), thimerosal and mercury – are not linked to the condition.

Addressing Specific Claims from the CDC: Aluminium and Certain Vaccines

The CDC’s edited page contends that some vaccines (DTaP, Hib, HepB, IPV and others) have not been studied adequately with regards to autism. It also points the finger at aluminium in vaccines.

It is broadly true that these vaccines have not been studied specifically with regards to autism. However, one study looked at 42 neuropsychological outcomes at ages 7 to 10 based on vaccines received in the first year of life, including many mentioned by the CDC. It found no adverse effect from the full, timely vaccine schedule vs. receiving fewer vaccines or less frequently.

For aluminium, the CDC criticises a Danish study on over 1.2 million children which found no link between autism or any of 49 other conditions and cumulative aluminium exposure from vaccines received up to age 2. The CDC’s criticism simply cherry-picks figures from the supplementary material (see attached picture): it does not invalidate the result.

What “No Evidence” Really Means

One of my favourite scientific papers of all time finds that “the effectiveness of parachutes has not been subjected to rigorous evaluation by using randomised controlled trials.”

So, is it reasonable to say the protective effect of parachutes “is not supported by science”?

Of course it is not. The key to understanding why is mechanism. If there is a mechanism – in this case, well-understood physics – we do not need systematic study to make a valid claim.

Conversely, if there is no science-based mechanism – as with vaccines and autism – we do not need specific studies to rule it out. On the contrary, anybody making such a claim would need to present actual evidence, rather than simply point to the absence of specific studies.